CCWD and SAM Joint Recycled Water Committee1307B359... · MINUTES CCWD & SAM JOINT RECYCLED WATER...

CCWD and SAM Joint Recycled Water Committee

7:00 PM, Monday, August 15, 2016

Coastside County Water District, 766 Main Street, Half Moon Bay, CA 94019

1. CALL TO ORDER / ROLL CALL

2. PUBLIC COMMENT / ORAL COMMUNICATION

3. OLD BUSINESS

4. NEW BUSINESS

A. Approve Minutes of May 16, 2016 Meeting

B. Clarification on Water Quality Needs – OCP

C. Agreement / Guiding Principles – SAM/CCWD/OCP

D. Direction on Design Scope of Work – SAM

5. ADJOURNMENT

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INFORMATION FOR THE PUBLIC

This agenda contains a brief description of each item to be considered. Those wishing to

address the Committee on any matter not listed on the Agenda, but within the jurisdiction of

the Committee, may do so during the Public Comment section of the Agenda and will have a

maximum of three minutes to discuss their item. Those wishing to speak on a matter listed on

the Agenda will be called forward at the appropriate time.

Any writing that is a public record and relates to an agenda item for an open session of a

regular meeting, that is distributed to the Committee less than 72 hours prior to the meeting, is

available for public inspection, during normal business hours, at the address listed above.

Committee meetings are accessible to people with disabilities. Upon request, this agenda will

be made available in appropriate alternative formats to persons with a disability. In compliance

with the Americans with Disabilities Act, special assistance for participation in this meeting can

be obtained by contacting Kathy Matthews at (650) 726-0124. Request for a disability-related

modification or an accommodation in order to participate in the public meeting must be made

at least two working days in advance of the meeting.

http://www.coastsidewater.org/

MINUTES

CCWD & SAM JOINT RECYCLED WATER COMMITTEE MEETING May 16, 2016

CALL TO ORDER: The meeting came to order at 7:06 p.m. at SAM Administration Building, located at 1000 N Cabrillo Highway, Half Moon Bay, CA. PRESENT: SAM General Manager Beverli A. Marshall, Kishen Prathivadi (SAM Engineering Construction and Contracts Manager), Clemens Heldmaier (MWSD), Scott Boyd (MWSD), Bill Huber (MWSD), Ric Lohman (GCSD SAM Board), Ken Coverdell (CCWD), Glenn Reynolds (CCWD), Mary Rogren (CCWD), Deborah Ruddock (HMB, SAM Board), Bruce Russell (OCP) 2. PUBLIC COMMENT/ ORAL COMMUNICATION - NONE 3. OLD BUSINESS

A. Approve Minutes of March 21, 2016 Following a brief discussion, Ken Coverdell moved and Scott Boyd seconded the motion to approve the minutes of the March 21, 2016 Joint Recycled Water Committee meeting.

B. SAM Status Update: General Manager Marshall stated that both MWSD and GCSD have approved funding for the recycled water project but the City of Half Moon Bay has questions and concerns they need to address before approving the funding for the project. She informed the Committee that the SAM Board had given direction for herself and Kishen Prathivadi to meet with the Member Agency Managers to try and answer the questions and concerns from Half Moon Bay so it could go back to their Council for consideration. She stated that Kishen is preparing a presentation for Friday, May 20th when the meeting will take place. A discussion ensued. Ken Coverdell requested an update of what happens at the May 20th meeting with the Member Agency Managers. Ric Lohman proposed writing the formal contracts between CCWD & SAM and CCWD & OCP before the 25% design. Kishen Prathivadi discussed the kick off meeting with the State Water Resources Control Board on April 6, 2016 in Sacramento and stated that Ric Lohman was also in attendance by telephone. Kishen discussed the funding, application and financial agreement steps and informed the committee that SAM would not be eligible for the facilities planning grant because it was already awarded to SAM several years ago. Ric Lohman commended Kishen on the amazing job he did getting everything together for the meeting and commented that he was pleasantly surprised at the eagerness of the SWRCB to help with whatever they can to get the project going. Debbie Ruddock requested an electronic copy of the presentation. C. CCWD Status Update: Ken Coverdell stated that they were waiting for the 25% design to move forward.

CCWD & SAM RWC Minutes of May 16, 2016 Page 2 of 2 D. Ocean Colony Status Update: Bruce Russell had no status update.

4. NEW BUSINESS A. Recycled Water Committee Meeting Schedule The next Recycled Water Committee meeting will be held on Monday, June 20th, 2016 at 7:00 PM at Coastside County Water District (CCWD), 766 Main Street, Half Moon Bay unless there are no updates, then the meeting will be rescheduled. 5. PUBLIC COMMENT/ORAL COMMUNICATION - NONE 6. ADJOURNMENT The meeting was adjourned at 7:44 p.m. Respectfully submitted,

Beverli A. Marshall General Manager

June 16, 2016 Ms. Beverli Marshall General Manager Sewer Authority Mid-Coastside 1000 N. Cabrillo Highway Half Moon Bay, CA 94019 Re: Coastside County Water District Recycled Water Quality Specification Dear Ms. Marshall: I write to inform you that the Board of Directors of Coastside County Water District (CCWD), at their meeting on June 14, 2016, voted to adopt a minimum water quality specification for recycled water to be provided to CCWD by Sewer Authority Mid-Coastside (SAM) as outlined in the Guiding Principles for Recycled Water Agreement Between SAM, CCWD, and MWSD (Principles). According to the Principles, SAM, as producer of the recycled water to be distributed by CCWD, will design recycled water treatment facilities to satisfy CCWD’s water quality requirements (Principle #3). The adopted minimum quality specification for recycled water is shown in Table 1 of Kennedy/Jenks Consultants’ Technical Memorandum #1: Phase 1 Recycled Water Project Water Quality and Quantity Evaluation (TM#1), in the column labeled “OCP Water Quality Requirement”. The attached staff report provides further details and includes a copy of TM#1. The District looks forward to continuing to work with SAM to realize the benefits water recycling offers our community. Please email or call me if you have any questions. Sincerely,

David R. Dickson General Manager

766 MAIN STREET, HALF MOON BAY, CALIFORNIA 94019 650-726-4405 www.coastsidewater.org

Kennedy/Jenks Consultants

p:\pw-proj\2015\1568022.00_ccwd phase 1 rw\09-reports\9.09_report\tm#1 water quality\tm#1 final\1568022 00_ccwd_rw_tm#1_waterqualquant_final_12-11-2015.doc © Kennedy/Jenks Consultants, Inc.

15 December 2015

Technical Memorandum #1 (FINAL)

To: David Dickson, General Manager, Coastside County Water District

Prepared by: Mary Trail, P.E. and Ryan Holloway, PhD.

Reviewed by: Craig Lichty, P.E.

Subject: Phase 1 Recycled Water Project Water Quality and Quantity Evaluation K/J 1568022*00

1 Introduction and Background

In January 2015, Coastside County Water District (District) approved the Guiding Principles for a Recycled Water Project between Sewer Authority Mid-Coastside (SAM), Montara Water and Sewer District (MWSD) and the District. The basis for agreement provides for SAM being responsible for treatment and disposal of wastewater, and the development of a recycled water treatment facility on their site that will generate water quality sufficient for the District’s and MWSD’s customers’ use. The Phase 1 Project is proposed to consist of two primary components:

1. A recycled water treatment facility at the SAM plant, the capacity of which shall be designed, at a minimum, to serve recycled water to Ocean Colony Partners (OCP) golf courses.

2. A recycled water transmission and distribution system for the District’s service area including delivery to OCP’s golf courses.

SAM is responsible for the design, construction, operation, CEQA and permitting of facilities on their site. The District and MWSD are responsible for the same items as they relate to transmission and distribution of recycled water from the plant to their customers. Flexibility for future expansion of supply and distribution to other customers will be included in the planning, design and construction of facilities.

The District desires to understand its customers’ specific water quality and quantity requirements for non-potable uses of recycled water. The Phase 1 customer base is OCPs’ golf courses. Other customers may be included in the future, but it is anticipated that other uses will have more stringent water quality requirements than those for golf courses.

This Technical Memorandum #1 (TM#1) summarizes the assessment of customer water quality and quantity requirements, including customer issues and regulatory water quality requirements.



David Dickson, General Manager, Coastside County Water District 15 December 2015 1568022*00 Page 2


2 Water Quality Evaluation

This section summarizes industry guidelines for water quality related to golf course irrigation, OCP-defined water quality requirements, the water quality of SAM effluent and treatment requirements required to reach the OCP-defined water quality requirements.

Table 1 summarizes the results of the water quality evaluation for golf courses, and subsequent sections provide supporting documentation for the information presented in Table 1.





Table 1: Water Quality Summary for Golf Courses

Degree of Problem(a)

OCP Water Quality

Requirement(b)

SAM Effluent Water Quality

(c)

Risk To Grasses

(b)

Meets OCP Criteria Water Quality Parameter Unit

Negligible Slight to Moderate Severe

Salinity

Electrical Conductivity (ECW) dS/m <0.7 0.7-3.0 >3.0 ≤1.1 1.2 Moderate No

Total Dissolved Salts (TDS) mg/L

<450 450-2,000 >2,000 ≤700 550 Moderate Yes

Soil Water Infiltration

Adj. SAR = 0-3 & EC = >0.7 0.7-0.2 <0.2 SARadj = 3 & EC = 1.1

SARadj = 5.0 & EC = 1.2

Moderate No Adj. SAR = 3-6 & EC = >1.2 1.2-0.3 <0.3

Specific Ions

Sodium (root absorption) SAR <3 3 - 9 >9 3 5 Moderate No

Sodium (foliar absorption) mg/L <70 >70 -- ≤70 104 Moderate No

Chloride (root absorption) mg/L <70 >70 -- ≤100 142 Moderate No

Chloride (foliar absorption) mg/L <100 >100 --

Boron mg/L <1.0 1.0-2.0 >2.0 ≤1 0.4 Negligible Yes

Other Important Constituents

Bicarbonate (HCO3) mg/L <90 90-520 >520 ≤250 277 Moderate No

pH Neutral 6.5-8.4 Acid/Basic 6.5-7.5 7.6 Negligible No

Table 1 Notes:

(a) Industry water quality guidelines for golf course irrigation, modified from Harivandi (2007). (b) Water quality requirements specified by OCP. (c) Average secondary effluent concentrations from samples collected on 8/18/15 and 8/31/15.





2.1 Water Quality Guidelines for Golf Course Irrigation

One of the most important assets to a golf course is the quality of its turfgrass. Warm-season grasses are generally more drought and salt-tolerant than cool-season grasses, with considerable variation in tolerance to salt and drought in each group. Successful golf course irrigation is dependent on knowing the salt content of the soil and irrigation water and understanding the relationship between salt content, soil conditions, and salinity tolerance of the turfgrass species. (Harivandi, 2007)

Recycled water is derived from wastewater, and it contains higher concentrations of dissolved salts than the original water supply source. Industry water quality guidelines for golf course irrigation focus primarily on the soil-water-plant-salt relationship. Irrigation management at golf courses requires monitoring of both soil and water quality, particularly salt content associated with sodium and chloride. Salt accumulation in the soil is the most common cause of plant toxicity and high salt content can damage or kill turfgrass. A high concentration of salts reduces water uptake in plants and increases the uptake of unwanted ions by plants. (Bilderback, et al)

Specific parameters of concern for turfgrass irrigation are: electrical conductivity (EC), total dissolved salts (TDS), sodium, chloride, boron, bicarbonate and sodium absorption ratio (SAR).

EC is a measure of how conductive a solution (e.g., water and salts, or soil, water, salts) is to an electrical current and is related to the concentration of TDS in any solution. A solution of water and soil not containing salts will have a high resistance to an electrical current and a low EC. Conversely, a solution of soil and water containing moderate to high concentrations of salts will be more conductive and have a higher EC.

The TDS is a measure of all salts contained in the water sample including sodium and chloride, which can harm turfgrass even at low concentrations (< 100 mg/L). The concentration of sodium, calcium, magnesium, and bicarbonate in the water are of particular importance because they are used to calculate the SAR of the recycled water

The SAR is a calculated value that indicates the concentration of sodium relative to that of calcium and magnesium in water. Water with a moderate or high SAR may reduce the soil permeability and increase salt accumulation in the soil. Whereas, water with a low SAR is less likely to affect the permeability of the soil, especially soils with high clay content. . Irrigation water having an SAR above 4 can result in root uptake of toxic levels of sodium. (Bilderback, et al.)

Local soils, climate and the type of grass being irrigated factor into the establishing the potential for problems associated with various water quality parameters. The likelihood of salt injury generally increases at golf courses with low annual precipitation, warm climates, slow-draining or impermeable (clay) soils, and cool-season grasses. Salt tolerance of plants is typically





expressed in relation to the salt content of the soil. Table 2 provides a guide to salt tolerance of grasses based on EC values of soil water. (Harivandi, 2007)

Because recycled water is a drought-proof and reliable source for golf course irrigation, water quality guidelines for using recycled water at golf courses have been established. Enclosure 1 provides a comparison of several industry references for using recycled water at golf courses.

Table 2: Relative Tolerance of Turfgrass Species to Soil Salinity

Sensitive (<3 dS/m) Moderately Sensitive

(3-6 dS/m) Moderately Tolerant

(6-10 dS/m) Tolerant

(>10 dS/m)

Annual bluegrass Annual ryegrass Perennial ryegrass Alkaligrass

Bahiagrass Buffalograss Creeping bentgrass Bermudagrass

Carpetgrass Creeping bentgrass Course leaf Fine-leaf

Centipedegrass Slender creeping, red and chewings fescue

Tall fescue Saltgrass

zoysiagrasses

Colonial bentgrass Seashore paspalum

Hard fescue St. Augustinegrass

Kentucky bluegrass

Rough bluegrass

Table 2 Notes:

(a) Sources: Harivandi (2007), WateReuse Foundation (2007). (b) Poa annua is the botanical name for annual bluegrass, Kentucky bluegrass and rough bluegrass.

2.2 OCP Water Quality Criteria

OCP Golf Course representatives provided information regarding their turf grass varieties and Table 3 summarizes the type of turfgrasses used at OCP golf courses and the degree of salinity sensitivity for each. These are all cool-season grasses and the most salt sensitive species, poa annua, is used throughout the golf course.





Table 3: OCP Turf Types and Tolerance to Soil Salinity

Location Types of Turfgrass Degree of Sensitivity

Greens Poa annua Creeping bentgrass

Sensitive Moderately Sensitive

Tees Poa annua Perennial ryegrass

Sensitive Moderately Tolerant

Fairways Poa annua Creeping bentgrass Perennial ryegrass

Sensitive Moderately Sensitive Moderately Tolerant

Rough Poa annua Perennial ryegrass Fine fescue

Sensitive Moderately Tolerant Moderately Sensitive

Table 3 Notes:

(a) Poa annua is the botanical name for annual bluegrass, Kentucky bluegrass and rough bluegrass.

2.3 SAM Effluent Water Quality

Secondary effluent was sampled by SAM and CCWD numerous times beginning in 1994. Samples were collected as part of an effort to measure constituents in SAM’s effluent that may be detrimental to turf grass health. The main constituents of concern for turfgrass and measured in SAM’s effluent were EC, total dissolved solids (TDS), sodium, chloride, calcium, magnesium, and bicarbonate.

Enclosure 2 provides a summary table of historical sampling data. Figures 1 through 3 illustrate how specific water quality parameters of concern have changed over time. The increase in concentrations of these parameters is likely due to water conservation efforts, which have had the effect of reducing wastewater flows and concentrating salt in the effluent. Additionally, reverse osmosis began in 2010 at one of the larger nurseries, and discharge of brine (salt) from the membrane treatment equipment has also increased salt levels in the wastewater.





Figure 1: EC and adj. SAR Concentrations (1994 to 2015)

Figure 2: SAR vs. EC (1994 to 2015)

EC Goal

SAR Goal





Figure 3: TDS, Cl and Na Concentrations (1994-2015)

Figure 1 indicates that the sodium absorption ratio and electrical conductivity values in SAM effluent exceed the OCP requirements. Figure 2 illustrates that although the SAR and EC have both been increasing over time, the relationship between the two parameter results in water quality that would not be expected to reduce the permeability/infiltration rate of the soil. Additionally, the ratio of SAR to EC has remained relatively constant (between 4.0 and 4.5). Lower SAR to EC ratios (low SAR high EC) is desirable because it indicates that the water has higher concentrations of calcium and magnesium that are beneficial to soil permeability. Figure 3 indicates that the TDS has remained well below the OCP goal, but chloride and sodium concentrations are both higher than the OCP goal.

SAM conducted a recycled water pilot study in 2009 using ultrafiltration membranes and ultraviolet (UV) disinfection. The pilot study proved the ability to meet California Code of Regulations Title 22 recycled water criteria for unrestricted use, but the treatment process does not remove sodium or chloride.

OCP expressed concerns regarding the quality of recycled water produced during the pilot study conducted because the recycled water quality would not meet the OCP’s prescribed water quality criteria shown in Table 1 for chloride and sodium. The OCP’s specific concerns with regards to these two minerals are salt accumulation in valves of the irrigation system and





tolerance of grass species to high levels of salts. Recycled water with these concentrations of sodium and chloride may require periodic flushing of greens to reduce salt buildup in the soil.

2.4 Treatment Required to Meet OCP Water Quality Requirements

All of the water quality parameters that do not meet OCPs requirements relate to salt content; treatment will be required to reduce salt. Reverse osmosis (RO) is the primary treatment technology that is used to separate salt from water. RO operates at relatively high pressure in a closed vessel where water is forced through a semi-permeable membrane that removes suspended and dissolved particles. The RO process is approximately 85% efficient, and the remaining 15% of the water applied to an RO membrane is rejected as brine; this is where the salt is concentrated.

The treated water (RO permeate) has 99.7% of the dissolved solids (including salts) removed. In order to achieve all of OCP’s water quality requirements, split treatment using RO will be required. Table 4 summarizes an analysis showing how much RO treatment would be required to meet OCP criteria for sodium and chloride, using historical SAM water quality data.

Table 4: RO Treatment Analysis Summary

SAM Effluent Water Quality(a)

OCP Criteria (mg/L) Required % RO

Treatment(b)

Sodium (mg/L) 2015 max = 105 Historical avg. = 106 Historical max = 133

70 32 – 48%

Chloride (mg/L) 2015 max = 143 Historical avg. = 147 Historical max = 173

100 30 – 42%

Table 4 Notes:

(a) Historical SAM effluent data summarized in Enclosure (2) was used to determine maximum and average values. "2015 max" is the highest concentration observed in the most recently sampled SAM effluent, August 2015.

(b) Percentage RO blending water is calculated using an RO membrane sodium and chloride rejection of 99.7%.

Table 4 illustrates that sodium rejection controls the RO sizing, and between 32 and 48% of the recycled water will need to be treated with RO, depending on the CCWD specifications for treatment requirements. CCWD may choose to specify that the RO blend be designed to meet the historical maximum sodium concentration (133 mg/L), in which case 48% treatment with RO would be required to meet OCP goals. CCWD may choose to specify some alternative product water goal, in which case the blending ratio may change. For instance, based on the 2015 effluent water quality data, 32% RO treatment would be adequate to meet OCP’s sodium requirements.





Table 5 illustrates how 48% RO treatment would impact the effluent water quality and the anticipated blended water quality, based on the most recent SAM effluent samples (August 2015).

Table 5: Anticipated Water Quality for Secondary Effluent, RO Product

Water and Blended Recycled Water for OCP

Water Quality Parameter SAM Effluent

Water Quality(a)

RO Water Quality

(b) SAM/RO Blend Water Quality

Total Dissolved Solids (mg/L) 555 2 292

Sodium (mg/L) 105 3.5 55

Chloride (mg/L) 143 3.1 75

Electric Conductivity dS/m 1.2 0.03 0.6

Sodium Adsorption Ratio 5.1 1.5 3.3

pH 7.6 1.7 6.5

Table 5 Notes:

(a) Highest value in SAM secondary effluent data measured in 2015. (b) RO water quality estimated from preliminary RO modeling effort, including MF and RO treatment processes.

The RO treated water is of a very high quality, low in TDS, sodium, and chloride. The SAM/RO blend water quality meets OCP’s water quality goals for TDS, sodium, chloride, and EC but the SAR of the blend (3.3) is slightly higher than the water quality goal (3.0). The SAR to EC ratio is also outside of the most acceptable range and may result in lower soil permeability. However, accumulation of salts in the soil due to lower soil permeability should be of less concern using the low-TDS SAM/RO blend. If soil permeability is a problem or concern, gypsum can be added to the blended water to reduce the SAR, increase the EC, and improve the SAR to EC ratio.

Because secondary effluent and conventionally filtered tertiary water cannot be effectively applied directly to RO membranes, a microfiltration (MF) membrane is typically used to remove suspended solids before RO. The treatment process that SAM will need to employ to meet OCPs requirements will be MF/RO of secondary effluent followed by either UV or chlorination disinfection. This treatment process will meet the California Code of Regulations Title 22 for Tertiary Recycled Water for unrestricted use and will meet OCPs water quality requirements.





3 Water Quantity Evaluation

This section summarizes the demand for recycled water and the effluent flowrates required to create a recycled water supply that meets the OCP’s supply requirements.

3.1 OCP Golf Course Demands and Existing Irrigation System

The OCP irrigation system serves 210 irrigated acres on the two OCP golf courses, and additional irrigation for Ritz Carlton Resort landscaping, a condominium complex adjacent to the Ocean Colony subdivision, greenbelt areas within the Ocean Colony subdivision, Miramontes Point Road landscaping and Spyglass subdivision park. OCP has provided the monthly and peak water demands, which are summarized in Tables 6 and 7.

Table 6: OCP’s Average Monthly Irrigation Water Demand(a)

Month Monthly Demand (acre-feet)

Monthly Demand (million gallons)

Daily Demand (gpd)

January 0 0 0

February 0 0 0

March 8.7 2.83 91,450

April 35.1 11.44 381,250

May 52.6 17.14 552,900

June 52.6 17.14 571,330

July 52.6 17.14 552,900

August 52.6 17.14 552,900

September 49.1 16.00 533,310

October 35.1 11.44 368,950

November 8.7 2.83 94,500

December 0 0 0

Total 347.1 113.10

Table 6 Notes:

(a) Monthly demand data provided by OCP is for average, non-drought conditions





Table 7: OCP’s Recycled Water Supply Requirements for Irrigation

Criteria Requirement

Average day Demand 550,000 gpd

Peak Day Demand 800,000 gpd

Instantaneous Peak Demand 2,880 gpm(a)

Irrigation Pump Capacity 3,600 gpm(b)

Irrigation Window 10pm to 6am

Table 7 Notes:

(a) OCP’s staff operate the irrigation pumping system at 80% of capacity, so the typical instantaneous peak demand is 0.8 x 3,600 gpm = 2,880 gpm.

(b) OCP operates three irrigation pumps for a total capacity of 3,600 gpm.

OCP operates three onsite irrigation ponds as storage facilities. The three irrigation ponds total approximately 9 million gallons of storage volume, but some sedimentation has reduced the total storage capacity to approximately 6.1 million gallons. Additional ponds are used as storage for stormwater and for aesthetics, but are not considered part of the irrigation system.

Currently, the irrigation ponds are filled from five groundwater wells located approximately 2.7 miles north of the OCP site, near Pilarcitos Creek and the SAM treatment facilities. The existing irrigation line conveys groundwater from the wellfield to the receiving pond at an average flowrate of 400 gpm and a peak flowrate of 450 gpm.

Transfer pumps are used to fill the other two irrigation ponds from the receiving pond. Three irrigation pumps are used to distribute water from the ponds into the irrigation system. The golf course also has two potable meter connections from CCWD. Potable water is infrequently used to fill the irrigation ponds and flush the turf-grass to remove salts that have accumulated in the soil as a result of regular irrigation with the groundwater supply.

OCP has indicated the normal operations of the pond and irrigation system will be the same, whether groundwater or recycled water is used for supply. Because operational storage is provided on the golf course site, the recycled water facilities at SAM would be sized to meet peak day irrigation demands at OCP, or 0.8 million gallons per day (mgd). It is assumed that treatment facilities on SAM site will provide for flow equalization upstream of the tertiary treatment and disinfection facilities, so these facilities can be reliably operated 24 hours per day, at OCP’s peak day demand (800,000 gpd).

The OCP peak day demand requirement of 800,000 gpd is 40% higher than the average day demand during the highest irrigation month of the year (571,330 gpd in June). The cost implications of potentially oversizing the treatment and disinfection facilities capacity is a significant level of service/cost trade-off that should be further discussed by the project participants.





3.2 Availability of SAM Effluent for Recycled Water Supply

Secondary effluent average dry weather flowrates (ADWF) at SAM peaked at nearly 1.8 mgd in 2006 and, except for a small increase in 2010, have been declining steadily over the last nine years. The summer of 2015 saw the lowest flows in 20 years, less than 1.2 mgd. Figure 4 illustrates the historical ADWF at SAM.

The decline can be attributed to long-term conservation efforts and the ongoing drought, the worst of record in California. Although the ADWF may rebound upon termination of the drought, the assessment of the availability of effluent for recycled water production is based on the current conditions to account for similar conditions during future droughts.

Figure 4: SAM Historical Average Dry Weather Flow

Figure 4 illustrates that the golf course peak day irrigation demand can be met under current flow conditions at SAM. The required supply of secondary effluent will be slightly more than the OCP peak day demand of 0.8 mgd, to account for the reject brine associated with RO treatment. Flow equalization basins at SAM may be necessary to meet the peak day demands, and would be included in the treatment process design performed by SAM.





Table 8 presents the RO flowrates and total secondary effluent requirement required to meet OCP’s requested level of service requirements related to water quality and quantity.

Table 8: RO Blending Requirements and Flowrates

SAM Effluent Water Quality

(a)

OCP Criteria (mg/L)

Required % RO

Treatment(b)

RO Flowrate, mgd

Total Req'd Secondary

Effluent Flowrate, mgd

(c)

Sodium (mg/L) 2015 max = 105 Historical avg. = 106 Historical max = 133

70 32 – 48% 0.26 – 0.38 0.84 – 0.86

Chloride (mg/L) 2015 max = 143 Historical avg. = 147 Historical max = 173

100 30 – 42% 0.24 – 0.34 0.84 – 0.85

Table 8 Notes:

(a) Historical SAM effluent data summarized in Enclosure (2) was used to determine maximum and average values. (b) Percentage RO blending water is calculated using an RO membrane sodium and chloride rejection of 99.7%. (c) Required secondary effluent flowrate calculated for a peak day irrigation supply requirement of 0.8 mgd.

Table 8 illustrates that the required RO flowrate to meet sodium goals varies from 0.26 mgd to 0.38 mgd, depending on the CCWD specifications for treatment requirements. It is possible to operate the RO system at a variable rate based on continuous monitoring of effluent quality to reduce operating costs when effluent water quality is relatively low in sodium. However, this strategy would require additional controls and would complicate operations. Therefore, it is recommended that the RO system be operated at a constant flowrate, regardless of variations in effluent water quality.

4 Conclusions

The following bullets summarize the conclusions for the water quality and quantity evaluation:

The water quality evaluation indicates that filtration alone will not provide water quality that meets OCP requirements.

RO treatment of approximately 32% to 48% of tertiary recycled water will be necessary to reduce the sodium and chloride levels to meet OCP requirements. The blending requirements are driven by sodium levels in the effluent.

A treatment facility capacity of 0.8 mgd would be required to meet OCP peak day demands. The actual volume treated on a given day would vary depending on specific





climatic conditions and irrigation needs. The RO system would be sized to meet a flow of 0.38 mgd for blending to meet specific water quality requirements.

RO treatment results in a 15% reject rate in the form of brine. Therefore, the secondary effluent flowrate needed to meet the 0.8 mgd production rate is estimated to be 0.84 to 0.86 mgd.

5 Project Cost Implications

5.1 Water Quality

The RO treatment required to meet OCP water quality requirements will substantially increase project costs. Many golf courses around the bay area are currently irrigating with recycled water that has similar characteristics to SAM effluent without RO treatment to reduce salts. However, these golf courses may be using potable water for periodic flushing to reduce salt buildup in the soils or they may have dual-plumbed facilities in which the greens and tees receive potable water for irrigation and recycled water is used to irrigate less sensitive areas. Enclosure 3 provides a water quality summary of four bay area water recycling facilities in comparison to SAM effluent.

The Olympic Club is irrigating with disinfected tertiary recycled water from Daly City's Wastewater Treatment Plant. Gypsum is added to the recycled water to enhance soil permeability. It is unknown if this type of process would be suitable for OCP, but could be explored further. If gypsum could be used to enhance soil permeability and reduce the effects of salts at OCP, RO split-treatment may not be needed, greatly reducing project costs. This option also opens up the tertiary treatment technology options that can be considered. If RO is eliminated, then MF is no longer needed for RO pretreatment. This issue is a significant level of service/cost consideration for the project stakeholders and should be evaluated carefully.

5.2 Treatment Facility Sizing

OCP has requested that the treatment and disinfection facilities be sized to a peak day demand of 0.8 mgd. This is 40% higher than the 0.57 mgd demand for the average day of the peak irrigating month and significantly impacts project costs. Project stakeholders may wish to explore an alternative operating scenario in which OCP uses recycled water to meet its peak month, average day demand conditions, and then uses groundwater wells as a backup supply to meet peak day demands. This is another very significant level of service/cost consideration for the project stakeholders.





6 References

Bilderback, T., Dole, J., & Sneed, R. Water supply and water quality for nursery and greenhouse crops [PDF document]. Retrieved from: http://www.nurserycropscience.info/water/source-water-quantity/extension-pubs/water-supply-and-water-quality-for-nursery-gh.pdf/view

Harivandi, A. (2007). Using recycled water on golf courses. Golf Course Management, 75(6), p. 98-108.

Huck, M., Carrow, R. N., & Duncan, R. R. (2000). Effluent water: nightmare or dream come true? Green Section Record, 38(2), p. 15-29.

Pace Turf. (2010). Water quality guidelines [PDF document]. Retrieved from https://www.paceturf.org/PTRI/Documents/water/0502water.pdf

Robbins, J. Irrigation water for greenhouses and nurseries [PDF document]. Retrieved from http://www.uaex.edu/publications/pdf/fsa-6061.pdf

SRT Consultants. (2008). Recycled Water Study for Sewer Authority Mid-Coastside.

WateReuse Foundation. (2007) Salinity Management Guide. Retrieved from http://www.salinitymanagement.org/Salinity%20Management%20Guide/cp/cp_7_table-1.html

Enclosures (1) Industry Standards: Water Quality for Golf Course Irrigation (2) Historical Water Quality Summary, SAM Effluent (3) Bay Area Recycled Water Quality Summary



Enclosure1:IndustryStandards:WaterQualityforGolfCourseIrrigationGolf Course Management (2007) Pace Turf (2010) USGA (2000)

Negligible Slight to Moderate Severe Low Medium High None Slight to Moderate Severe pH 6.5 to 8.4 TDS mg/L <450 450 ‐ 2,000 > 2,000 <450 450 ‐ 2,000 > 2,000 <450 450 ‐ 2,000 > 2,000 Elec Conductivity dSM <0.7 0.7 ‐ 3.0 >3.0 <0.7 0.7 ‐ 3.0 >3.0 <0.7 0.7 ‐ 3.0 >3.0 Boron mg/L <1.0 1.0 ‐ 2.0 >2.0 <0.5 0.5‐3.0 >3.0 <0.7 0.7‐3.0 >3.0 Chloride

Root absorption meq/L <2 2 ‐ 10 >10 mg/L <70 70 ‐ 355 >355 <70 70 ‐ 355 >355 Foliar absorption meq/L <3 >3 ‐‐ <3 >3 ‐‐

mg/L <100 >100 ‐‐ <105 >100 ‐‐ <100 >100 ‐‐ Sodium

Root absorption SAR <3 3 ‐ 9 >9 <70 70‐210 >210 Foliar absorption meq/L <3 >3 ‐‐ <3 3‐9 >9

mg/L <70 >70 ‐‐ <70 70‐200 >200 <70 >70 ‐‐ Adj SAR Bicarbonate meq/L <1.5 1.5 ‐ 8.5 >8.5 <1.5 1.5 ‐ 8.5 >8.5 mg/L <90 90 ‐ 500 >500 <92 92‐520 >520 <90 90 ‐ 500 >500 Residual Chlorine mg/L <1.0 1 ‐ 5 >5 Soil Water Infiltration

if SAR = 0 ‐ 3 & Ecw = dSM >0.7 0.7 ‐ 0.2 <0.2 >0.7 0.7 ‐ 0.2 <0.2 >0.7 0.7 ‐ 0.2 <0.2 if SAR = 3 ‐ 6 & Ecw = dSM >1.2 1.2 ‐ 0.3 <0.3 >1.2 1.2 ‐ 0.3 <0.3 >1.2 1.2 ‐ 0.3 <0.3 if SAR = 6 ‐ 12 & Ecw = dSM >1.9 1.9 ‐ 0.5 <0.5 >1.9 1.9 ‐ 0.5 <0.5 >1.9 1.9 ‐ 0.5 <0.5 if SAR = 12 ‐ 20 & Ecw = dSM >2.9 2.9 ‐ 1.3 <1.3 >2.9 2.9 ‐ 1.3 <1.3 >2.9 2.9 ‐ 1.3 <1.3 if SAR = 20 ‐ 40 & Ecw = dSM >5.0 5.0 ‐ 2.9 <2.9 >5.0 5.0 ‐ 2.9 <2.9

Sources: Harivandi, 2007; Pace Turf, 2010; Robbins, J.


Technical Memorandum #1 (FINAL) Enclosure2:HistoricalWaterQualitySummary,SAMEffluent

SAM Effluent Pilot Plant results SAM October 22, 2009 SAM Effluent

(Jan ‐ Dec 2010) SAM Effluent (Jan/Feb 2011) CCWD SAMPLES

Nov/Dec 1994 9/16/2009 9/29/2009 9/16/2009 9/29/2009

Sample A Pilot Plant Effluent

Sample B Storage

Tank, OCP

Sample 1 Pilot Plant Effluent min max ave min max ave 8/18/2015 8/31/2015

pH 6.8‐7.2 10.8 7.4 7.6 6.8 7.7 7.3 6.5 7.4 7.057143 7.6 7.6 TDS mg/L 540‐580 450 440 450 440 1210 730 646 380 576 482 524 572 552.4286 544 555 Elec Conductivity dSM 760‐840 980 950 960 980 1.89 1.14 1.01 0.707 1.22 0.994 1.05 1.15 1.098571 1.17 1.14 Boron mg/L 0.22‐0.64 0.32 0.4 0.31 0.4 0.28 0.34 0.38 0.25 0.49 0.35 0.26 0.45 0.345714 0.34 0.35 Chloride mg/L 120‐140 140 120 140 120 226 118 122 107 178 140 138 173 154.7143 143 141 Sodium mg/L 110‐130 100 84 96 82 367 66 109 74 120 102 104 133 117 105 103 Adj SAR 3.12‐4.21 4.59 3.71 4.38 3.62 38.71 3.51 5.14 2.96 5.15 4.35 3.76 5.17 4.475 5.05 4.86 Bicarbonate meq/L 180 200 180 200 308 242 306 158.6 370.9 276.6 268.4 330.6 307.4429 285.5 268.4



Enclosure3:BayAreaRecycledWaterQualitySummaryDaly City

(2013‐2015) South Bay Water Recycling (2015) Sunnyvale (2010)

Silicon Valley Clean Water (SBSA, 2006)

Marin Municipal Water District (2013)

range ave range range range range pH 6.3‐7.3 6.9 7.4‐8.1 6.6‐7.2 8.1‐8.2 6.9‐8.1 TDS mg/L 160‐1,300 513 432‐764 588‐1,038 710‐800 647‐894 Elec Conductivity dSM 0.009‐1.9 0.985 0.8‐1.3 1.1‐1.6 1.5‐1.6 1.0‐1.4 Boron mg/L 0.13‐0.43 0.22 0.4 0.3‐0.4 0.52 n/a Chloride mg/L 24‐1,000 104 123‐187 212‐320 300 145‐239 Sodium mg/L 55‐94 74 91‐143 155‐208 203 126-178

Adj SAR 1.1‐4.2 3.1 3.3‐4.6 4.2‐5.4 7.2‐7.3 3.6-5.2

Bicarbonate meq/L 24‐380 309 90‐171 78‐228 268‐303 69‐85

CCWD and SAM Joint Recycled Water Committee1307B359... · MINUTES CCWD & SAM JOINT RECYCLED WATER...

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